Controller for electric motors



1944- R. B. HUNTER ETAL 2,359,473

CONTROLLER FOR ELECTRIC MOTORS Filed Feb. 15, 1945 L m ql L2 I r z5a" mmm W 9 Patented Oct. 3, 1944 CONTROLLER FOR ELECTRIG MOTORS Richard B.Hunter, Shorewood, and Jesse E.

Jones, Wauwatosa, Wis., assignors to Cutler- Hammer, Inc., Milwaukee,Wis., a corporation of Delaware Application February 13, 1943, SerialNo. 475,7 76

12 Claims.

This invention relates to controllers for electrlc motors, and moreparticularly to controllers affording so-called jam protection.

In Patent No. 1,579,018, March 30, 1926, two forms of drum type motorcontrol, one of the plain reversing type and the other of the dynamiclowering type are disclosed with jam protection which has been foundvery advantageous in practice. In the first mentioned form of controlthe protective mean is responsive, as for example when the motor stallsduring operation in either direction, to re-include a predeterminedamount of series resistance, whereas in the second mentioned form theprotective means so functions but only when the motor is operating inhoisting direction.

In both cases when the protective means responds the same remainseffective pending return of the control drum to off position.

The present invention has among its objects to improve both controllersdisclosed in the afore mentioned patent, the improvements includingprovision for low voltage protection during running and during jamming.

Another object is to simplify the means emplayed to afford jamprotection and to obtain low voltage protection through the medium ofinstrumentalities used for jam protection.

Another object is to provide a drum controller with jam protecting meanscomprising electromagnetic contactors so utilized a to take arcing towhich the drum contacts otherwise would be subjected.

Another object is to enable use of a jam relay having normally opencontacts, such a relay being less susceptible to shocks and vibrations,and hence more suitable for use on shipboard,

Another object is to provide jam protective mean functioning withoutinterruption of motor torque.

Another object is to provide jam protective means applicable todifferent types of drum controllers, as for example a plain reversingdrum or a dynamic lowering drum without change in the control circuitsof said means and hence enabling for control of such circuits a standardarrangement of drum contacts.

Another object is to provide improved jam protective means applicable tocontrollers other than those aforementioned, whereas various otherobjects and advantage of the invention will hereinafter appear.

Certain embodiments of the invention are diagrammatically illustrated inthe accompanying drawing which will now be described, it beingunderstood that the embodiments illustrated are susceptible of variousmodifications without departing from the scope of the appended claims.

In the drawing,

Figure 1 shows the invention applied to a plain reversing controller;

Fig. 2 shows a modification of the drum portion of the jam protectivemeans, and

Fig. 3 shows the invention applied to a dynamic lowering controller.

Referring to Fig. 1, the same shows a drum type reversing controlleressentially like that shown in the aforementioned patent but with theaddition of mean affording a shunt for the motor armature to be closedin the off position of the drum and in the first forward and reversepositions of the drum. More specifically Fig. 1 shows a motor M havingan armature A and a series field winding F to be supplied with powerfrom lines LI and L2. The drum comprises contact fingers l to 5 andcooperating segments la, 2a, 3a, 4a and 2b, 3b, 4b, ED for control of'the direction of operation of the motor through reversals of the flowof current through the motor armature. Additionally the drum comprisescontact fingers B and 1 and cooperating segments 6a and la, controllingan armature shunt for motor M including a resistor r. Additionally thedrum includes contact finger 8, 9, H), H, I2 and I 3 and cooperatinsegments 8a to I31; and 8b to I32) which afford variation and exclusionof a series resistor R for the motor when the motor is caused to operatein either direction. The aforementioned reversing contacts provid forconnection of the motor to line LI, whereas the motor connections toline L2 include a drum contact finger l4 and cooperating segments Ma andMb.

The jam protective means includes an electromagnetic contactor N, anelectromagnetic contactor J and an electro-responsive jam relay JR. Thecontactor N has normally disengaged contacts l5 which when engagedcomplete circuit from line L2 to and through the windin l6 of the relayJR to drum contact finger I4. Thus line connection of the motor isdependent upon engagement of the drum finger M by one of its cooperatingsegments and also upon engagement of the contacts [5 of contactor N,whereas establishment of this connection subjects the winding I6 ofrelay JR to the motor current. The relay JR has normally disengagedcontact I! which when engaged tend to complete an energizing circuit forthe winding I8 of contactor J, this contactor having normally disengagedcontacts I9 which when engaged establish a circuit for jam protection.This circuit extends from a tap of series resistor R, which tap forillustration is shown as drum contact I2, to and through contacts I9 ofcontactor J to line L2, and when contactor J responds to establish thiscircuit it acts through its normally engaged contacts 20 to interruptthe circuit of the winding 2! of .contactor N to cause the lattercontactor through its contacts I to interrupt the first mentionedconnection to line L2, As will be understood the portion of the resistorR thus reinserted for protection on jamming may be varied by adjustmentof the tap of resistor R connected to the contacts of relay J.

Here it is to be noted that the jam relay JR is of the normally opentype with the advantage aforementioned, and that both of the contactorsJ and N in respect of their main contacts I9 and I5 are of the normallyopen type. Moreover both contactors J and N are alike in having normallydisengaged auxiliary contacts 22 and 23, respectively, and differ onlyin that contactor J has the aforementioned normally engaged contacts 20.Hence it will be apparent that the two contactors may be of like size.

Considering now the control means for the contactors J and N, itincludes drum contact fingers 25, 2B, 2'! and 28, the contact finger 25having a connection to line LI and having a continuously engagingsegment 25a. The segments 26, 2! and 28, on the other hand, havecooperating segments 26a, 28a and 21b, 28b. Contact fingers 26 and 2!are electrically connected, and segments 28a and 26a are connected tosegment 25a while segments 28!) and 21!) are also connected to segment25a. Thus when segment 28a is engaged with finger 28 circuit iscompleted from line LI to segment 25a and segment 28a to contact finger28 by conductor 29 through normally engaged contacts 20 of contactor J,to and through the winding 2| of contactor N to line L2, and the sameconnections are com pleted when contact finger 28 is engaged by segment2%. One or the other of these segments engages contact finger 28 uponinitial movement of the drum to start the motor in either direction, andthus provision is made for immediate energization of relay N to engageits contacts I5 whereby when the drum reaches its first operativeposition the motor line connections will be completed. When this occursdrum contact finger 26 will be'engaged by segment 26a or drum contactfinger 2'! will be engaged by segment 21b and this establishes aconnection from line LI to drum contact 25, and thence to drum contact2! or contacts 26 by conductors 3i) and 3| to and through the nowengaged contacts 23 of contactor N by conductors 32 and 29 to andthrough the winding 2| of contactor N as already traced. This circuitmaintains the winding 2| energized when contact finger 28 is disengagedby its cooperating segment 28a or 28b. Also engagement of drum contact26 or 2! by its respective finger provides a connection renderingclosure of the contacts i! of relay JR effective to connect the windingI8 of contactor J across lines LI, L2. More particularly circuit may betraced as already described from line LI to conductor 30, thence throughcontacts I! to and through winding I8 to line LI.

Thus With the motor operating in either direction response of the jamrelay JR to an overload current in the motor circuit energizes windingI8 to cause response of contactor J with the res lt of engaging its.contacts I9 to complete the jam protective circuit aforedescribed. Atthe same time contactor J through disengagement of its contacts 20deenergizes contactor N and through engagement of its contacts 22completes a shunt around contacts I! of relay JR. Accordingly thecontactor J upon responding establishes for itself a maintaining circuitwhich maintains said contactor energized pending return of the drum todisengage from finger 26 or 21, as the case may be, its cooperatingsegment. If meanwhile the relay JR has released to disengage itscontacts I! this will have no effect on contactor J, whereas whencontactor J is released by the aforementioned return movement of thedrum the motor is disconnected from line L2 and the starting cycle maybe repeated.

Here it is to be noted that when jamming orccurs contactor N remainsenergized until deenergized by opening of contacts 20 of contactor J,thus providing continuous motor torque during the transfer from runningconnections to jam connections. Also it is tobe noted that if whilecontactor J or contactor N is energized there is a failure of voltage oran abnormal drop in voltage such contactors will release to entirelydisconnect the motor from line L2 and to necessitate return of the drumto starting position in order to reconnect the motor to line L2. Thiswill be apparent for the only energizing connections for the contactor Nwhen the drum is in the running position will be interrupted by the thenopen contacts 23 of said contactor, whereas the connections for thewinding I8 of contactor J will be opened both at the contacts I! ofrelay JR and at the then open contacts 22 of relay J. Further it is tobe noted that with the contactor J or the contactor N closed movement ofthe drum to off position provides for immediate deenergization thereof,causing it to take arcing to which otherwise the drum contacts would besubjected.

Fig. 2 shows a slight modification of the drum section constituting partof the jam protective means, the modification consisting in substitutingfor drum segments 28a and 28b of Fig. 1 a single segment 280 to engagecontact finger 28 in the off position of the drum and to disengage itwhen the drum is moved to either its first forward position or its firstreverse position. Thus as is obvious this modification provides forenergization of contactor N in off position of the drum rather than uponinitial starting operation of the drum as in Fig. 1. This modifiedcontrol may be desirable under certain conditions.

Fig. 3 shows a dynamic lowering drum similar to that shown in theaforementioned patent, the motor MI of Fig. 3 being shown as having anarmature A, a series field F and a shunt field FI. This drum has forcontrol of the motor circuits substantially the same contact arrangementas that of said patent, providing in off position a closed loop for themotor armature and field F, which loop includes a resistor rI, providingin its hoist positions a circuit through the motor armature and field Fin series, and providing in its lowering positions a loop for the motorarmature and field F with line connection of said loop such as to placethe motor armature and field F in a parallel relation for reversal ofthe flow of current through the motor armature while maintaining theoriginal polarity of the field F. The drum has resistance controllingcontacts to afford suitable resistance control for both hoisting andlowering and like the drum of Fig. '1 it has contacts between the motorand both sides of the supply line except as regards the shunt field Flwhich is permanently connected to line LI and connected to line L2through certain of the drum contacts.

In the control of Fig. 3 the jam protective means is the same as in Fig.l, but in Fig. 3 the winding N3 of the jam relay JR is connected betweenthe motor armature and the drum contacts which provide for connection toline Ll for hoisting. Thus this relay winding is subjected to the motorcurrent during hoisting, whereas it is not in circuit during lowering,this providing for protection against jamming in hoisting and insuringagainst undesired action of the protective means in lowering. Yet asaforestated the jam protective means remains the same as in Fig. 1 evento the arrangement of the drum contacts forming part thereof.

As in Fig. 1 the contactor J of Fig. 3 controls circuit between a lineL2 and a tap of the motor controlling resistor and the action of theprotective means in hoisting is the same as explained in connection withFig. 1. In lowering contactor J never responds because relay JR is notin circuit and hence is unresponsive. Thus in lowering contactor Nlikewise is freed from influence by relay JR through contactor J,whereas in hoisting it is subject to control by relay JR throughcontactor J as explained in connection with Fig. 1. Accordingly it willbe obvious that the protective means while modified in action to theextent indicated otherwise functions as in Fi 1 with retention of itsadvantageous characteristics aforedescribed including that of affordinglow voltage protection.

What We claim as new and desire to secure by Letters Patent is:

1. Control means for establishing operating connections and a jamprotective connection for an electric motor, comprising a normally openelectroresponsive switch requiring energization for normal motoroperation, a normally open electroresponsive switch to be energized toestablish a jam protective motor connection and to deenergize the formerelectroresponsive switch, and a normally open jam relay responsive toenergize the second mentioned switch.

2. The combination with an electric motor, of control means to establishselectively difierent motor connections for normal operating conditionsand for protection on jam, said means comprising for selection of suchconnections sep-' arate electroresponsive switches each of the normallyopen type and further comprising a jam relay of the normally open typeresponsive to motor current to effect selection of the second mentionedconnections.

3. In an electric motor controller, the combination with control meansto establish motor connections for normal operating conditions, saidmeans comprising a manual control device and an electroresponsive switchof the normally open type under the control of said manual device, er anormally open jam relay and a normally open electroresponsive switchresponsive under the control of said relay to establish protective motorconnections and to maintain such protective connections independently ofsaid relay but subject to control by said manual device.

4. In an electric motor controller, the combination with control meansto establish motor connections for normal operating conditions, saidmeans comprising a manual control device and an electroresponsive switchof the normally open type under the control of said manual device, of anormally open jam relay and a normally open electroresponsive switchresponsive under the control of said relay to establish protective motorconnections and to maintain such protective connections independently ofsaid relay, but subject to control by said manual device, the firstrecited electroresponsive switch being subject to deenergization byresponse of the last recited electroresponsive switch.

5. In an electric motor controller, the combination with control meansto establish motor connections for normal operating conditions, saidmeans comprising a manual control device and an electroresponsive switchof the normally open type under the control of said manual device, of anormally open jam relay and a normally open electroresponsive switchresponsive under the control of said relay to establish protective motorconnections and to maintain such protective connections independently ofsaid relay but subject to control by said manual device, the firstrecited electroresponsive switch being subject to deenergization byresponse of the last recited electroresponsive switch, and the firstrecited switch when deenergized requiring for reenergization thereofmanipulation of said manual device.

6. The combination with a drum controller for electric motors, of anelectroresponsive switch controlled by said drum controller and coactingtherewith to establish motor connections for normal motor operations, ajam relay and an electroresponsive switch under the control of saidrelay and said drum controller jointly to coact with said drumcontroller to establish protective motor connections, the last recitedswitch upon so functioning causing opening of the first recited switch,said drum controller having an arrangement of contact fingers andsegments for control of said electroresponsive switches such that nochange in drum control of said electroresponsive switches is neededwhether the drum controller is of the plain reversing type with the jamrelay effective for reverse motor operations or is of the dynamiclowering type with the jam relay effective only in hoist direction.

7. The combination with a drum controller for electric motors, of anelectroresponsive switch controlled by said drum controller and coactingtherewith to establish motor connections for normal motor operations, ajam relay and an electroresponsive switch under the control of saidrelay and said drum controller jointly to coact with said drumcontroller to establish protective motor connections, the last recitedswitch upon so functioning causing opening of the first recited switch,said electroresponsive switches being of the normally open type, andsaid drum controller having an arrangement of contact fingers andsegments for control of said electroresponsive switches such that nochange in drum control of said electroresponsive switches is neededwhether the drum controller is of the plain reversing type with the jamrelay effective for reverse motor operations or is of the dynamiclowering type with the jam relay effective only in hoist direction.

8. The combination with a drum controller for electric motors, of anelectroresponsive switch of the normally open type controlled by saiddrum controller and coacting therewith to establish motor connectionsfor normal motor operations, of a jam relay and an electroresponsiveswitch of the normally open type under the control of said relay andsaid drum controller jointly to coact with said drum controller toestablish protective motor connections, the last recited switch uponresponding causing opening of the first recited switch and establishingfor itself a maintaining circuit independent of said relay but subjectto control by said drum controller, said drum controller having anarrangement of contact fingers and segments for control of saidelectroresponsive switches such that no change in drum control of saidelectroresponsive switches is needed whether the drum controller is ofthe plain reversing type with the jam relay effective for reverse motoroperations or is of the dynamic lowering type with the jam relayeffective only in hoist direction.

9. The combination with a drum controller for electric motors, of anelectroresponsive switch of the normally open type controlled by saiddrum controller and coacting therewith to establish motor connectionsfor normal motor operations, a jam relay of the normally open type, andan electroresponsive switch of the normally open type under the controlof said relay and said drum controller jointly to coact with said drumcontroller to establish protective motor connections, the last recitedswitch upon so functioning causing deenergization of the first recitedswitch and establishing for itself a maintaining circuit independent ofsaid jam relay but controllable by said drum controller, and said drumcontroller having an arrangement of contact fingers and segments forcontrol of said electroresponsive switches such that no change in drumcontrol of said electroresponsive switches is needed whether the drumcontroller is of the plain reversing type with the jam relay effectiveonly in the hoist direction.

10. The combination with a drum controller for electric motors, of anelectroresponsive switch of the normally open type controlled by saiddrum controller and coacting therewith to establish motor connectionsfor normal motor operations, a jam relay of the normally open type andan electroresponsive switch of the normally open type under the controlof said relay and said drum controller jointly to coact with said drumcontroller to establish protective motor connections, the last recitedswitch upon so functioning causing deenergization of the first recitedswitch and establishing for itself a maintaining circuit independent ofsaid jam relay but controllable by said drum controller, and said drumcontroller having an arrangement of contact fingers and segments forcontrol of said electroresponsive switches such that no change in drumcontrol of said electroresponsive switches is needed whether the drumcontroller is of the plain reversing type with the jam relay effectivefor reverse motor operations or is of the dynamic lowering type with thejam relay efiective only in the hoist direction, the aforementionedarrangement of contact fingers and segments being such that the firstrecited switch when deenergized requires for reenergization thereofpositioning of said drum controller to afford motor starting protection.

11. In an electric motor controller, in combination, a normally openelectroresponsive switch requiring energization for normal motoroperation, a normally open electroresponsive switch to be energized toestablish a jam protective connection and to deenergize the formerswitch, said switches under predetermined low voltage conditionsinsuring disconnection of the motor, and control means for said switchesincluding a jam relay responsive to energize the second mentioned switchand requiring energization for energization of the second mentionedswitch after release of the latter resulting from low voltage, andfurther including for control of the first mentioned switch means whichmay be set to prevent automatic response of the first mentioned switchupon restoration of normal voltage following release of the firstmentioned switch through drop in voltage.

12. In an electric motor controller, in combination, control means toestablish motor connections for normal operation, said means comprisingan electroresponsive switch in the motor connections to open underpredetermined low voltage conditions, and further comprising a controlde-- vice for said switch having starting and running positions andrequiring return to starting position for energization of said switchafter its re lease as a result of low voltage, and jam protec tive meansincluding an electroresponsive switch responsive only under jamconditions to establish an alternate motor connection and to deener izethe first mentioned switch, the second mentioned switch releasing underpredetermined low voltage conditions to interrupt said alternate motorconnection.

RICHARD B. HUNTER JESSE E. JONES.

